Swivel construction for a chair

ABSTRACT

An improved chair swivel includes a housing tube which may be attached to the chair legs. Within the tube is a stationary cam and a movable cam. The movable cam is attached to a spindle that engages the chair seat. The movable cam is biased into engagement with the stationary cam and has a normal rest position. Upon rotation of the chair seat, the movable cam is driven from the normal rest position by the spindle. Release of the force on the chair seat permits the seat to return to its normal rest position.

United States Patent 1 1 [111 3,837,61 1 Rhoades Sept. 24, 1974 [54]SWIVEL CONSTRUCTION FOR A CHAIR 3,385,550 5/1968 Doerner 248/417 [75]Inventor: Nolan K. Rhoades, Beloit, Wis.

Primary Examiner-Casm1r A. Nunberg Asslgneel Keystone consolld-atedIndustries Attorney, Agent, or Firm--Molinare, Allegretti, Newitt Inc.,Peoria, 111. & wit f [22] Filed: Oct. 1, 1973 1 11 Appl. No.: 402,347ABSTRACT An improved chair swivel includes a housing tube [52 U.S. c1248/417, 248/425, 297/349 may l attached to the legsw'thm 51 Int. ClB60n 1/02 F16m 13/00 a stat'mary cam and a mvable The ble cam isattached to a spindle that engages the [58] Field of Search 248/417, 41,425; 297/349, 3

297/383. 108/140 chair seat. The movable cam 18 biased into engagementwith the stationary cam and has a normal rest [561 2:532:32:tsxzssiztfnzi'125 32122335 1: UNITED STATES PATENTS spindle. Release of theforce on the chair seat permits l,895,226 l/l933 KUpSkl 1 248/4l7 theeat to return to normal rest position. 3,212,816 10/1965 Nordmark248/417 X 3,223,376 12/1965 Ciuffini et al 248/417 5 Claims, 8 DrawingFigures \W lenses es u l 1 SWIVEL CONSTRUCTION FOR A CHAIR BACKGROUND OFTHE INVENTION In a principal aspect, the present invention relates to animproved chair swivel construction and, more particularly, to a swivelconstruction that is self-centering.

Swivel chair mechanisms and self-centering swivel chair mechanisms havebeen heretofore known. Such mechanisms permit the seat of a chair to berotated relative to the legs. Upon removal of the force required toeffect the rotation, the seat will return to its normal rest or centeredposition.

Preferably, a mechanism which will accomplish this result is compact,easy to install, easy to service and inexpensive to manufacture. Anothercharacteristic desired in such mechanisms is reliability. It is withthese objectives in mind that the present invention was conceived.

SUMMARY OF THE INVENTION In. a principal aspect, the present inventioncomprises the combination of a chair including a leg portion and aseparate seat and an improved mounting and swivel mechanism forattaching the seat to the leg portion. The swivel includes a cylindricalhousing with a stationary cam fixed in the lower end of the housing. Amovable cam is biased against the stationary cam so that the camsurfaces of the movable and stationary cam are engaged. The movable camrotates with a spindle that is attached to the chair seat. The biasedcams tend to drive the seat to a centered or rest position.

It is thus an object of the present invention to provide an improvedchair swivel and mounting mechanism.

It is a further object of the present invention to provide a chairswivel mechanism utilizing a minimum number of parts wherein the swivelhousing is shaped to cooperate with a stationary cam to hold that cam ina substantially fixed position within the housing.

It is a further object of the present invention to provide a chairswivel mechanism having a pair of complementary cams which serve tocenter or return the chair seat to a predetermined desired positionwhenever a turning force is released from the swivel.

Another object of the present invention is to provide a spring operatedchair swivel mechanism having a memory characteristic.

These and other objects, advantages and features of the presentinvention will be set forth in greater detail in the description whichfollows.

BRIEF DESCRIPTION OF THE DRAWING In the detailed description whichfollows, reference will-be made to the drawing comprised of thefollowing figures:

FIG. 1 is a cross-sectional view of the improved swivel and chaircombination of the present invention;

FIG. 2 is a cross-sectional view taken along the line 22 in FIG. 1;

FIG. 3 is a cross-sectional view of a swivel mechanism taken along theline 3-3 in FIG. 1;

FIG. 4 is a cross-sectional view of the swivel mechanism taken along theline 4-4 in FIG. 1;

FIG. 5 is a cross-sectional view of the swivel mechanism taken along theline 55 in FIG. 1;

FIG. 6 is a cross-sectionalview taken along line 6+6 in FIG. 1; l

FIG. 7 is a plan view of the complementary cams utilized in the chairswivel mechanism ofthe present invention; and i a FIG. 8 is a front planview of the stationary cam utilized in the swivel mechanism of thepresent invention.

DESCRIPTION OF THE EMBODIMENT The combination of the invention will bedescribed principally by reference to FIG. 1, although the other figuresshould be viewed, particularly the discussion of the shapes ofnon-cylindrical portions of the device. FIG. 1 discloses across-sectional view of a swivel 16 incorporated with a chair seat 1 0and chair legs 18. The chair seat 10 is attached by braclget arms 12 toacenter, cylindrical mounting tube 14. The tube 14 receives a shaft 68extending from the swivel 1 6. The opposite end of the swivel I6 isfixed to legs l8i The attachment of the swivel 1 6, to the legs 18 isdiscussed in greater detail below.

The swivel 16 includes a generally cylindrical tube 2Q having alongitudinal axis 22. The lower end of the tube 20 includes a taperedsection 24 and terminates with a narrowed polygonally shaped end FIG. 3illustrates the cross-sectional shape of the end 2 6 The opposite end ofthe tube 2() terminates with an outwardly extending flange 28 A groove30. adapted to receive a retaining ring is provided near the upper endof the tube 20. I

Positioned within the tube 20 is a stationary cam 34, preferably madefrom a plastic material such as Celcon. The cam 34 is generallycylindrical. However, earn 34 includes at its lower end a complementarytapered section 3Q which cooperates with tapered section 24 of tube 2 0to prevent movement of the cam along the longitudinal axis 22 throughthe lower end of the tube 20. The cam 34 also includes a lower polygonalcross section portion 38 which is complementary with the end 26 of tube2Q. In this manner, the cam 34 is maintained in a non-rotative positionin tube 20. The cam 34 also includes a projecting end stud, 40 which isfur-. ther illustrated in the cross-sectional view of FIG. 2. The stud40 cooperates with a retaining ring 42 in a manner to be describedbelow. a

A spindle 44 which is generally cylindrical and concentricallypositioned on axis 22 is mounted with its lower end 46 in a pocket 48defined in cam 34. The pocket 48 has a circular cross section asillustrated in FIG. 4. The lower end 46 of spindle 44 has double oropposite side flats for cooperation with a movable cam 5.0. Thus,movable cam 50 as illustrated in FIG. 5 includes a center opening 52having apairof flats so that cam 50 and spindle 44 rotatecoincidentally. Cam 50 is also preferably made from a plasticsuch asCelcon plastic. I

The cams 34 and 50 include complementary cam surfaces 54 and 56respectively. The particular shape and function of these surfaces willbe set forth in greater detail below during discussion of FIGS. 7. and'8 The movable cam 50 is maintained constant contact with the stationarycam 34 by means of aspring 60. Spring 60 is maintained against the uppersurface of cam 50 by means of an E ring 62 which is maintained in agroove 64 of spindle 44. The E ring bears against an upper bearing 66for spindle 44. The upper bearing 66 is, in turn, maintained in positionby the re tainer ring 32 in the groove 30. Note that the bearing 66serves to maintain the alignment of the spindle 44.

An outer extension or shaft 68 of the spindle 44 projects intocooperation with the tube 14 in the manner previously described.Preferably, the shaft 68 is tapered. Typically, the taper would be a No.3 Morse taper, a taper configuration well known to those skilled in theart.

FIGS. 7 and 8 illustrate the configuration of cam surfaces 54 and 56 ofcams 34 and 50. The stationary cam 34 includes a continuouscircumferential surface 54 having a substantially horizontal lowersurface land 70 and continuously ascending surface portions 72 and 74 oneither side of the lower land 70. At a point 180 from the lower land 70is a substantially horizontal planar land or crest 76.

The complementary upper or movable cam 50 includes a lower horizontalengagement crest 78 which cooperates with the total surface 54. Forexample, crest 78 engages the lower land 70 when the swivel is in therest position. Since the cam 50 is continuously biased by spring 60, thesurface crest 78 will always tend to seek the lower land 70. This istrue regardless of the position of the crest 78 on the surface 54 sincethe surfaces 72 and 74 are continuously ascending with no detentpositions.

Referring again to FIG. 1, the swivel of the present invention may bemounted in a chair leg tube 82 by using an adapter cap 84 which isattached to the cylindrical tube 20 and engages against flange 28. Thus,if the leg tube 82 has, for example, a polygonal cross section, the cap84 may act as a transition piece to attach the swivel 16 to the tube 82.

The cap 84 includes a downwardly extending flange 86 which may be weldedor otherwise press fitted onto the tube 82. Preferably, a retainer ring42 is included and attached to the stud 40 to hold the swivel 16 withinthe tube 82 and also to assist in centering the swivel 16 within thetube 82. An alternative construction or means for attaching the swivel16 to a chair leg tube 82 provides for a smaller tube 82 and welding theflange 28 to such a smaller tube.

In use, the spindle 44 and attached cam 50 rotate coincidentally withthe seat 10. The tube 20 and stationary cam 34 move in unison with thelegs 18 and associated leg tube 82. Thus, due to the compression forceof the spring 60, the seat will normally be in a rest or a neutralposition determined by the relationship of the land 78 of cam-50 andlower land 70 of stationary cam 34.

However, seat 10 may be rotated manually or otherwise. This will causethe movable cam 50 to rotate. Thus, the land 78 of cam surface 56 willfollow the cam surface 54 and will remain in position to return the seat10 to its rest or neutral position upon release of the rotative forcethat causes the spindle 44 to turn. The swivel 16 thus has a memorycharacteristic. When not in use, the chair is effectively biased to aneutral position. After turning, the seat will return to its neutral ornormal unused position.

The invention which has been described is, therefore, to be limited onlyby the following claims and their equivalents.

What is claimed is:

1. In combination with a chair of the type including a leg portion and aseparate seat, an improved mounting and swivel mechanism for attachingthe seat to the leg portion, said swivel comprising in combination:

a hollow generally cylindrical tube with a longitudinal swivel axis,said tube having a lower end which is of decreasing diameter and atleast in part polygonally shaped; stationary cam member in said tube,said cam including a tapered, polygonal portion cooperative with thelower end of the tube to hold the cam in a substantially non-rotatableand downwardly nontranslatable position, said stationary cam includingan upwardly facing cam surface with a central pocket;

a spindle fitted in said pocket and extending upward along thelongitudinal axis from said tube, said spindle mounted for free rotationin said cam pocket, said spindle including a projecting shaft forengaging a mounting plate for the seat;

movable cam mounted on the spindle in the tube for rotative movementwith said spindle, said cam being translatable on the spindle andincluding an active cam surface engaging the stationary cam surface; and

spring means in said tube for biasing the movable cam against thestationary cam including means for retaining the spring in said tube,said cam surface of said stationary cam being a continuous closed looppath including a lower centered position and an upper active positiondiametrically opposite the lower position, said positions beingconnected by continuously ascending cam paths whereby the tube isconnected to the leg portion and the spindle to the seat, the seat beingnormally maintained in a fixed orientation relative to the leg portionas determined by the lower cam position, movable to any otherorientation by rotation of the seat and spindle and returnable to thelower position by the force of the biased spring on the cams.

2. The combination of claim 1 wherein said spindle is tapered andengages a cylindrical tube attached to the seat.

3. The combination of claim 1 including a cap having a downwardlydepending flange attached to outside of the tube, said cap beingengageable with a chair leg tube.

4. The combination of claim 1 including a retainer spring attached tothe lower end of the swivel for engaging a chair leg tube.

5. The combination of claim 1 including a spindle bearing in said tubeadjacent the end of the spring opposite the movable cam, said retainingmeans cooperative to mount said bearing and simultaneously maintain saidspring within said tube.

1. In combination with a chair of the type including a leg portion and aseparate seat, an improved mounting and swivel mechanism for attachingthe seat to the leg portion, said swivel comprising in combination: ahollow generally cylindrical tube with a longitudinal swivel axis, saidtube having a lower end which is of decreasing diameter and at least inpart polygonally shaped; a stationary cam member in said tube, said camincluding a tapered, polygonal portion cooperative with the lower end ofthe tube to hold the cam in a substantially non-rotatable and downwardlynon-translatable position, said stationary cam including an upwardlyfacing cam surface with a central pocket; a spindle fitted in saidpocket and extending upward along the longitudinal axis from said tube,said spindle mounted for free rotation in said cam pocket, said spindleincluding a projecting shaft for engaging a mounting plate for the seat;a movable cam mounted on the spindle in the tube for rotative movementwith said spindle, said cam being translatable on the spindle andincluding an active cam surface engaging the stationary cam surface; andspring means in said tube for biasing the movable cam against thestationary cam including means for retaining the spring in said tube,said cam surface of said stationary cam being a continuous cLosed looppath including a lower centered position and an upper active positiondiametrically opposite the lower position, said positions beingconnected by continuously ascending cam paths whereby the tube isconnected to the leg portion and the spindle to the seat, the seat beingnormally maintained in a fixed orientation relative to the leg portionas determined by the lower cam position, movable to any otherorientation by rotation of the seat and spindle and returnable to thelower position by the force of the biased spring on the cams.
 2. Thecombination of claim 1 wherein said spindle is tapered and engages acylindrical tube attached to the seat.
 3. The combination of claim 1including a cap having a downwardly depending flange attached to outsideof the tube, said cap being engageable with a chair leg tube.
 4. Thecombination of claim 1 including a retainer spring attached to the lowerend of the swivel for engaging a chair leg tube.
 5. The combination ofclaim 1 including a spindle bearing in said tube adjacent the end of thespring opposite the movable cam, said retaining means cooperative tomount said bearing and simultaneously maintain said spring within saidtube.